1. Field of the Invention
The present invention relates to a system and method for measuring conicity using four force-sensors, in which a spindle attached to a tire and four force-sensors are used to measure lateral force generated in the tire, individual signals measured by the four force-sensors of the spindle are amplified, a data acquisition (DAQ) board for converting an analog signal measured by the four force-sensors into a digital signal is prepared, and the digital signal, a delta load and a factor are used to calculate the conicity.
2. Description of the Related Art
A tire is manufactured using a number of half-finished products such as a tread, a belt, a carcass, a bead, etc., and thus has a roundness defect. To evaluate roundness or uniformity, most tires are subjected to uniformity testing.
Such characteristics are referred to as non-uniformity, and can be broadly classified according to stiffness, size and mass. Thus, non-uniformity of a tire is measured with respect to each of stiffness, size and mass.
If non-uniformity is too low or high, there are problems of vehicle vibration. Particularly, conicity affects leaning of the vehicle and is calculated from lateral force measured by a sensor, as shown in FIG. 2.
Devices for measuring uniformity of a tire include low speed and high-speed uniformity devices. These two devices are classified according to measurement capability within a speed range wherein vibration most often occurs under real world driving conditions. In general, a low-speed uniformity device can measure uniformity of a tire at a speed of less than 60 RPM (4˜7 km/h), while a high-speed uniformity device can measure uniformity of a tire at a speed of 60 RPM (200 km/h) or higher.
Taking device costs, measurement cycle speed, measuring methods, etc. into account, low-speed uniformity devices have generally been to evaluate products manufactured in a factory line, while high-speed uniformity devices have generally been used for the purpose of research.
A typical high-speed uniformity device employs eight force sensors in a spindle so as to measure conicity, and uses the equation shown in FIG. 4 in order to calculate conicity.